The water flow detection device is installed in a pipe in a fire extinguishing system such as a sprinkler system and a foam extinguishing system and detects water flow in the pipe to output a predetermined signal (fire signal, alarm signal). Inside of the water flow detection device is a check valve structure and divided into a primary chamber and a secondary chamber by the valve body. The valve body is in a closed state in which the primary chamber and the secondary chamber are separated from each other at all times. The primary chamber and the secondary chamber are filled with water at all times. A pipe connected to the primary chamber is connected to a water source such as a water tank and a pipe connected to the secondary chamber is connected to a spray head such as a sprinkler head and a foam head.
There are various water flow detection devices according to a detection method. For example, an actuated valve type water flow detection device is known which mechanically detects a differential pressure generated between the primary side and the secondary side of the valve body when water flows and outputs a signal such as a fire signal and an alarm signal. The water flow detection device has various advantages. For example, the amount of water flow for actuating the valve to output an alarm is constant and stable, there is no water path connected to another system, such as an alarm water path of an automatic alarm valve type water flow detection device, so that no influence such as reverse flow is exerted from other systems, and the device can be formed simply (see Patent Document 1 as an example of a conventional automatic alarm valve type water flow detection device).
Patent Document 1: Japanese Unexamined Patent Application Publication No. 09-103515